Telomere instability and the formation and transmission of radiation induced DNA damage

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CSC - Cost-sharing contracts

Objective

The new insights in telomere maintenance and telomerase activity as keypoints in tumour. The increased knowledge in induction and repair of DNA damage have raised large concern in the link between two process. TELORAD aims to determine the mechanistic link between telomerase, telomere binding protein and DNA repair gene and their respective role in the radiosensitivity. Mechanisms of stabilisation of the broken end, start point to the transmission of the radiation induced damage will be studied. Long term consequences as gene amplification and chromosome imbalance will be researched to identify the involvement of telomere maintenance in Hypersensitivity of individuals.TELORAD shows that telomere radiosensitivity and telomere capping are significant steps in the formation and transmission of radiation-induced damage. Clear associations with DNA damage response and tumour development are emerging in respect of chromosomal instability associated with the structure/ function of the telomeric repeat sequences that cap the ends of chromosomes. Telomere metabolism is closely linked to certain DNA repair proteins and shortening and alteration of telomeres can trigger apoptotic response and/or chromosomal instability and/or amplification via post-irradiation cycles of telomeric fusion-breakage-fusion.1. The telomere length is one of the biological determinants of radiation sensitivity in mammals.2. Human ITS are not hotspots for chromosome breakage; specific chromatin structure could induce such hot spots.3. The analysis of the mechanisms of capping of radiation-induced DNA breaks is crucial for understanding the biological consequences of exposure to ionizing radiation.4. DNA repair gene defects increase the probability of gene amplification.

During Telorad project the following technical breakthroughs were set up-Use of combined SKY/Q-FISH technology for identification of the involvement of telomeres in chromosomal aberrations.-Easy and quick technique to measure telomere length.-Technical development of DBD-FISH procedure, to be adapted for human, mouse, and Chinese hamster cells.-Simultaneous quantification of SSB and DSB in single cells, in the whole genome or within specific DNA sequence areas.-A new sensitive and reliable protocol for the non-radioactive detection of telomerase activity in cell culture protein extracts.-A new assay to analyze the induction and the persistence of aneuploidies in binucleated cells at interphase. This assay can also be applied to aneuploidies resulting from telomere shortening or dysfunction in mice.